It is often required to machine a component somewhat remotely. This is becoming more common in advanced manufacturing, particularly in the aeronautic industries where the tendency is towards larger and larger monolithic components. Large monolithic components have fewer joints that can be a source of weakness. Nevertheless, while this may reduce the need for machining of components, it does not entirely remove it, and it may render what is needed somewhat more complex. Even multiple component parts often require machining in hard-to-reach places after their initial construction. Wing parts are a case in point.
However, robot arms are versatile and flexible and can carry machine tools into hard-to-reach places. Remote optics or other guidance can precisely position the end of a robot arm. There are several issues that need to be addressed. First of all, the tool at the end of a robot arm must be compact; first, to fit into any confined space, but secondly to be able to position a working tool bit of the tool in selected positions in the confined space. Next, although, ultimately, precise positioning is perfectly possible, it is difficult to move a remote arm, if it is long and flexible, without small movements being exaggerated at the tool head by the flexibility of the arm and the distance of the tool head from the stable base of the robot.
When machining components it is invariably necessary to provide a reaction member against which the tool performing the machining can react in response to loads imparted by the workpiece in reaction to the action of the machining tool. However, in hard-to-reach places, providing such reaction member is often problematic. One approach is to employ a rigid mounting for the machining tool, but in confined spaces, maneuvering such a member is a problem and may limit the position at which the tool can be located. However, employing a more slender mounting reduces the stiffness and reaction force that can be applied.
It is known to use the workpiece itself as a steady reaction base. By clamping the tool to the workpiece, it does not matter if the tool working bit moves uncontrolled with respect to the ground, provided it maintains a true relationship with the workpiece. However, such an arrangement requires a means of advancing the tool working bit into or against the workpiece, increasing the bulk and complexity of the tool head.
Furthermore, controlling the position of the tool working bit while any such clamp is activated is difficult. It involves predicting the position of the tool working bit once the clamp is effected; and that depends, to a large extent, on the nature of the workpiece, which inevitably varies from case to case. Connecting such a clamp to a workpiece in a confined space is another problem.
Regardless of the mounting arrangement and the requisite reaction member, the issue of traversing the machining tool relative to the workpiece and with respect to its mounting, in confined spaces, is problematic. It is desirable that the machine tool is not bulky, since this limits its maneuverability. Yet the function of precisely traversing the tool bit relative to the workpiece is often a fundamental requirement. For example, in drilling a hole in a workpiece, the drilling tool must:
provide a mounting to resist drill-skating during initial startup of the hole;
provide a reaction member to resist reaction forces primarily axially with respect to the rotation axis once drilling progresses
provide means to advance the drilling bit as drilling progresses.
Consequently, it is an object of different aspects of the present invention, on the one hand to render a tool having tool bit advancement means as compact as possible, and, on the other hand, to provide means whereby accurate positioning of the tool working bit can be assured after clamping of the tool to a workpiece.
In another aspect, it is an object of the invention to provide a mounting structure for securely locating a device with respect to a substrate and to permit adjustment of part of the device with respect to the substrate, and subsequent locking of the device with respect to the substrate. While application of such a means to the machining of workpieces is clear from the first aspects of the present invention, the objective of the present aspect is not to be limited in that way.